Determination of P-wave velocity in concrete
Project no. 718 · Status: Kapanmış · 2016
Summary
Destructive testing methods such as core sampling have limitations on determination of damages particularly in structures such as high-rise buildings, tunnels, bridges and dams. Importance of nondestructive testing methods which were developed to eliminate these limitations has been increasing day by day. While some of these methods are electromagnetic based, some of them are based on propagation of elastic waves in a material and detection of them by appropriate sensors. P-wave (primary wave) is one of these elastic waves that propagate in a material with highest velocity and thus is used for defect detection as it is the first motion hitting a sensor. While the wave propagates through the different materials, its velocity changes due to dissipation of wave’s energy. By this means, defects in the materials such as cracks, voids or discontinuities can be easily determined. Thus, accurate determination of this velocity is important and has direct effect on calculation of defect location. In this study, ultrasonic-echo (UE) and acoustic emission (AE) methods were used as non-destructive testing methods in order to determine P-wave velocity in concrete. P-wave velocity propagating the concrete was first measured with a UE-based low frequency ultrasonic test device. Then, the AE activities generated by the Hsu-Nielsen pencil lead breaking test were analyzed and processed. By localizing these AE activities by source localization analysis, a P-wave velocity was determined and both UE and AE results were compared. As a result, a successful P-wave velocity determination was obtained in concrete with a difference of 2%.